Field of the Invention
This invention relates generally to organic light emitting diodes (OLEDs) and, more particularly, to an organic light emitting diode having a conductive electrode with enhanced light emitting properties.
Technical Considerations
An organic light emitting diode (OLED) is a device having an emissive layer that emits electromagnetic radiation, such as visible light, in response to the application of an electric current. The emissive layer is located between two electrodes (an anode and a cathode). When electric current is passed between the anode and the cathode (i.e., through the emissive layer), the emissive layer emits electromagnetic energy. OLEDs are used in numerous applications, such as television screens, computer monitors, mobile phones, personal digital assistants (PDAs), watches, lighting, and various other electronic devices.
OLEDs provide numerous advantages over conventional inorganic devices, such as liquid crystals used for displays and incandescent or compact fluorescent lamps (CLFs) and other lighting applications. For example, an OLED functions without the need for a back light. In low ambient light, such as a dark room, an OLED screen can achieve a higher contrast ratio than conventional liquid crystal displays, OLEDs are also thinner, lighter, and more flexible than liquid crystal displays. OLEDs require less energy to operate and can provide cost savings compared to incandescent or compact fluorescent lamps.
However, one disadvantage with OLED devices is that a significant amount of the electromagnetic energy generated by the emissive layer is not emitted from the OLED device. A large portion of the generated electromagnetic energy is trapped within the OLED device due to the “optical waveguide effect” caused by the reflection of electromagnetic radiation at the interfaces of the various layers of the OLED device. In a typical OLED fighting device, about 80% of the visible light emitted from the emissive layer is trapped inside the OLED device due to this optical waveguide effect. Thus, only about 20% of the light generated by the emissive layer is actually emitted by the OLEO device.
It would be advantageous to provide an OLED device in which more electromagnetic radiation produced by the emissive layer is emitted from the OLEO device, compared to conventional OLED devices. For example, it would be advantageous to provide a way to reduce the optical waveguide effect in at least one layer of the OLEO device to increase the OLED emission. It would also be advantageous to provide a method of making an OLED device having a reduced optical waveguide effect to promote increased electromagnetic emission from the OLED device.